U.S. Secretary of Defense Ashton Carter walks on his way to meet Japan's Prime Minister Shinzo Abe at Abe's official residence in Tokyo, Japan, 08 April 2015. Carter kicked off his first Asian tour on Wednesday with a stern warning against the militarisation of territorial rows in a region where China is at odds with several nations in the East and South China Seas. REUTERS/Franck Robichon/Pool